Levofloxacin is ideal as a first-line fluoroquinolone for the treatment
of urinary tract infections (UTIs) because of its broad antibacterial
spectrum and its favourable pharmacokinetics with almost complete
bioavailability (interchangeability of intravenous and oral route)
and mainly (> 80%) renal excretion of the parent, active drug
with a serum half-life allowing standard once daily dosing. For
acute uncomplicated UTIs such as acute cystitis, a 3-day course
of levofloxacin 250 mg once daily is recommended. For acute uncomplicated
pyelonephritis and mild to moderate complicated UTIs, a dose of
250-500 mg once daily for 5-10 days is usually sufficient. In more
severe or hospital-aquired UTIs, which are often caused by less
susceptible strains, the dose can further be increased up to 750
mg, as there is evidence of good clinical tolerance of levofloxacin.
Because of increasing resistance among uropathogens (especially
Escherichia coli) against conventional antimicrobials like
ampicillin and trimethoprim-sulfamethoxazole (TMP-SMX), fluoroquinolones
are used as first line treatment of both complicated and uncomplicated
UTIs. In some areas, however, an increase in resistance of E.
coli against fluoroquinolones can also be observed. UTI treatment
strategies need to be developed to slow down the emergence of resistance.
Reduced consumption of antibiotics, easing of selection pressure
by using different antibiotic classes, and appropriate dosing to
eradicate the causative, susceptible pathogens and to block the
growth of the most resistant, single-step mutants are possible strategies.
Pharmacokinetic (PK) and pharmacodynamic (PD) studies especially
designed for the treatment of UTIs and tested by appropriate clinical
studies are urgently needed.